Medical valving devices typically valve fluids injected into and withdrawn from a patient. One exemplary type of medical valving device, known in the art as a “catheter introducer,” maintains a sealed port for accessing the patient's vasculature. Use of such a valve enables vascular access without requiring the patient's skin to be repeatedly pierced by a needle. Moreover, catheter introducers are constructed to withstand a range of back-pressures produced by a patient's blood pressure, thus minimizing blood loss resulting from fluid injections or withdrawals.
Fluid commonly is transferred to/from a patient by inserting a syringe into a medical valve, thus communicating with the patient's vasculature. Problems arise, however, when the syringe is withdrawn from the valve. More particularly, a back pressure (i.e., a proximally directed pressure) produced by the withdrawing syringe undesirably can cause blood to leak proximally into various parts of the valve. In addition to coagulating and impeding the mechanical operation of the valve, blood in the valve also compromises the sterility of the valve.
The art has attempted to minimize fluid drawback by forcibly reducing the volume of an interior fluid chamber when the valve is closed. In particular, one such type of valve aimed at solving this problem has extra mechanical parts to compress a member that defines such a fluid chamber. See, for example, U.S. Pat. No. 5,921,264 (Paradis), which requires additional cantilever fingers and other cooperating mechanical parts to purportedly accomplish this function.
In addition to requiring more parts for this purpose, another type of valve forces a compressible member into a reduced diameter lumen, consequently forcibly reducing the volume of the fluid chamber. See, for example, U.S. Pat. No. 6,152,900 (Mayer), which uses this technique to purportedly solve the drawback problem.
Both noted purported solutions create additional problems. In particular, adding more parts increases the manufacturing cost of the valve. For example, more parts typically increases material cost, assembly time, and testing time. Moreover, the additional parts must cooperate in a proper manner to ensure that the valve operates as intended. In other words, a defect in one of the additional parts can adversely affect the mechanical operation of the valve. Furthermore, accurately forcing a compressible member into a reduced diameter lumen after such member has expanded can be difficult, thus possibly rendering the valve unusable.